1. Field of the Invention
The present invention relates to an image processing apparatus which can create an image file having a layer management function in which a plurality of image data is managed in a plurality of layers.
2. Description of the Related Art
An image processing apparatus is connected to each section in a company or to a network established in the company so that it has been increasingly shared by a plurality of users as a MFP (Multi-Function Product) which performs scanning, faxing and mailing as well as printing.
Recently, it becomes important to provide security in such image processing apparatus connected to the network. For example, when image data (including an image of a document data) is printed to be used, there is a case where the limited number of copies is used because the data contains contents which should not be presented to anyone outside of the company. There is a technique in which tint block data is additionally and inconspicuously printed in such image data and when the image data is copied, the tint block data becomes clear so that it is known that the data is copied. For example, there is known a technique to print a shadow of a seal to be registered in registration certificate together with a tint block which becomes clear when it is copied (refer to Japanese Utility Model Registration No. 3079230, for example). In addition, there is known an anti-counterfeit printed material which is shown as a forgery when it is copied by a color-copying machine (refer to Japanese Patent Laid-open Publication No. 7-89215, for example).
In addition, there is known a technique which limits a total print copies of document data to be printed by the MFP in a delivery destination, to the number of copies intended by a document composer, as shown in Japanese Patent Laid-open Publication No. 2003-333224. Furthermore, there is known a method of registering an available application every user so as to limit it, as shown in Japanese Patent Laid-open Publication No. 2003-229978. Still further, there is known a technique in which a scan document scanned by the MFP is linked to security information for that document, as shown in Japanese Patent laid-open Publication No. 2003-304352.
However, as described above, when the image data and the tint block data are superimposed to one image file, the image data cannot be used alone. Meanwhile, when the image data and the tint block data are separately delivered, it could be illegally used by someone.
Meanwhile, there is a PDF file as an image file in which the image data and the tint block data can be contained in one image file, they can overlap with each other as an image at the time of printing, and only the image data can be retrieved and used according to need. The PDF file comprises at least one layer and when it comprises a plurality of layers, there is provided a layer management function which can overlap the layers to be one image. Therefore, creating the image file which can manage layers, such as the PDF file in which the image data and the tint block data are stored in the different layers, only the image data can be retrieved and edited when it is necessary. However, that image file is also available for anyone as described above, which could be a problem.